1. Field of the Invention
This invention relates to a closure device for laminated paper containers, with the closure device arranged on the container over an opening of the container.
2. Description of Prior Art
Conventional containers of laminated paper have a cubic basic shape and are for packaging liquid products, in particular products of the food industry. The construction of the laminated papers used from the outside to the inside have the following layer sequence: polyethylene film; cardboard; polyethylene; aluminum layer; and polyethylene.
In this multi-layered material which is usually called laminated paper, with containers having a closure device, in the surface of the container in the laminated paper there is a predetermined opening. With the predetermined opening, a pre-cut opening normally has the upper three layers cut through, with the lower two layers of aluminum and polyethylene completely intact.
The closure devices are for containers of laminated paper which are known in two basic types. With an older type the container is already opened and the opening is sealed with a seal which can be pulled back. After removal of the seal the container is sealingly closed by the closure device attached onto the container. Accordingly, such closure device has a lower part with a pouring-out opening and a cover pivotally mounted thereon which closes the pouring-out opening with a sealed wall that sealingly engages into the pouring-out opening.
The seal is destroyed either by tearing open or by perforating or cutting, using a device which is arranged on the cover. This variation however requires the cover in a completely opened condition to be transported, stored and handled, by which there exists the danger of an undesired destruction of the seal.
Thus closure devices of a second type have been developed wherein the container of laminated paper is unopened and comprises only a predetermined opening. Such a predetermined opening may be of various types. Mostly several layers of the laminate are cut through and only the inner plastic layer and the aluminium layer lying thereover are still intact, as previously described.
The predetermined opening may have various forms, specifically one which is longitudinally separable and forms two tabs which may be laterally folded away from or of a single U-shaped tab which may be folded away to the rear.
Such predetermined openings must thus be pierced and cut open. For this purpose, for example, U.S. Pat. No. 4,934,590 shows a conventional closure device.
The closure device described here has, present in the lower part, a pivotal push-piece which serves for completely cutting open the predetermined opening and thereafter moving the corresponding U-shaped tab out of the pouring-out region to the rear. However, in the original position the push-piece which is to cut open the predetermined opening lies exposed and thus is completely unprotected against undesired or wanton destruction. The actual cover is simultaneously used as an actuation lever which in the original position is completely opened. At the same time, the surface of the cover coming to position into the container to the inside before closure for the first time is always exposed to contamination. For the mentioned reasons, such conventional closure device has not succeeded in the market.
The problem of keeping the tab from the region of the pouring-out opening has not been solved with known closure devices. The push-piece which is specifically positively and pivotally connected to the cover with this embodiment is then actually only pressed to the rear when the cover is closed. In this position, when the cover is completely opened the push-piece is completely freely pivotal and is moved forwards by the tab, because of the material elasticity, as when the container is relatively full, gets into the flow of the exiting contents by which means the pouring-out jet is interrupted.
One object of this invention is to provide a closure device of the mentioned type but without the known problem.